When I create my time-series data, how do I know that it's scaled correctly? When I replicated the complex conjugate prior to the ifft, I doubled the number of points, so I guess I'm not entirely sure.

I believe I am correct, because if I do the sum(abs(y).^2), that is equal to the mean g^2/Hz from the original PSD, which leads me to believe I've satisfied Parseval's theorem.